10 Plant Special Cell – Cotton Fiber 1

Cotton fibers are single-celled outgrowths from individual epidermal cells on the outer integument of the ovules in the developing cotton fruit. Fibers of upland cotton (G. hirsutum L.) generally grow up to 30 to 40 mm in length and 15 μm in thickness at full maturity. Their development consists of four overlapping stages: fiber initiation, cell elongation, secondary wall deposition, and maturation. The thickened secondary walls of mature cotton fibers have long been considered unique in that they were thought to consist of nearly pure cellulose and to be devoid of hemicellulose and phenolics. However, other plant derived fibers such as flax (Linum usitatissimum L) and ramie (Boehmeria nivea L) fibers have been shown to contain phenolics except cellulose (Angelini et al., 2000; Day et al., 2005).